1. Technical Field
The present disclosure relates to a unique valve system that is adapted to permit egress of gases and/or fluids in two directions. In particular, the present disclosure is directed to a valve system that is adapted to limit or regulate the peak inspiratory pressure of gases delivered to patients, while also limiting or regulating the peak pressure permitted downstream on the opposite side of such valve system.
2. Background Information
A variety of techniques and systems have been developed to assist physicians in treating or assisting patients with inhalation and/or ventilation issues. In many of these techniques, valving systems are desirable to ensure that the patient encounters or experiences the optimal pressure within the inhalation and/or ventilation system during the stages of inhalation and exhalation. Numerous relatively complicated pressure limiting valves, and pressure limiting systems, are known for controlling the peak inspiratory pressure of ventilation gas delivered to a patient, e.g, an infant, during manual ventilation.
Among known valve systems are reusable, adjustable metal pop-off valves which incorporate a spring and disc. These valve systems generally function to control the peak inspiratory pressure of ventilating gas once the preset threshold is attained. An issue with these pop-off valves is the possibility that the patient will be exposed to excess ventilation gas in the period when the pressure is building toward the preset threshold, a condition referred to as xe2x80x9cPositive End Expiratory Pressurexe2x80x9d or xe2x80x9cPEEP.xe2x80x9d Illustrative valving systems are described in a series of U.S. Patents which are assigned to Vital Signs, Inc. (Totowa, N.J.). U.S. Pat. No. 4,180,066 to Milliken et al. describes an anesthesia gas scavenging system that includes a first negative pressure relief valve and a second valve which provides both positive and negative pressure relief. The second valve, which is illustrated in FIGS. 3 and 4, includes a pair of discs (32, 40) which are movable relative to each other and to the valve housing. Disc 32 is mounted to a spindle which translates through an aperture in disc 40 to permit venting through apertures 42 in response to a negative pressure within the gas scavenging system. Disc 40, in turn, is spring biased by coil spring 38 into sealing engagement with raised ridge 30, but is adapted to move against the bias of spring 38 in response to a sufficient positive pressure within the gas scavenging system. The Milliken ""066 two disc valve system, which is highly tolerance-dependent, is particularly suited to a gas scavenging system and relies on a relatively complex set of motions to achieve its desired effects.
U.S. Pat. Nos. 5,301,667 and 5,425,358 to McGrail et al. disclose a pressure limiting valve for a ventilation gas apparatus which is adapted to independently vent in response to pressures above a peak inspiratory ventilation gas pressure and a base line pressure. In a disclosed embodiment, a spring is provided which biases a disc into engagement with a valve seat. The force delivered by the spring establishes or determines the peak inspiratory pressure, because a higher pressure within the gas ventilation apparatus is required to overcome the spring bias so as to vent the system. A disclosed embodiment further features a bleed hole or aperture which functions to establish and/or control the base pressure within the ventilation system.
A further exhalation valve for inhalation therapy is disclosed in U.S. Pat. No. 4,298,023 to McGinnis. The McGinnis ""023 exhalation valve features a valve closure disc that is biased into engagement with a valve seat by a plurality of constant force compression springs. Through the use of the constant force compression springs, the McGinnis ""023 exhalation valve advantageously maintains a desirable airway pressure within the inhalation system at a substantially constant pressure over a relatively wide range of flow rates. A commercial product incorporating, inter alia., the teachings of the McGinnis ""023 patent has been successfully marketed by Vital Signs, Inc. (Totowa, N.J.) for several years.
Despite the careful attention that has been given the design of valving systems for use with inhalation and/or ventilation systems by those skilled in the field, a need for improvement remains. In particular, exhalation valves of the type disclosed in the aforementioned McGinnis ""023 patent would benefit from features adapted to address exigencies that might be encountered during use.
According to the present disclosure, an exhalation valve is provided which advantageously functions to advantageously maintain a desirable airway pressure within an inhalation system at a substantially constant pressure over a relatively wide range of flow rates. The exhalation valve of the present disclosure also advantageously provides a further venting feature which obviates the potential for undesirable pressure build-ups within the inhalation system in the event certain exigencies are encountered during use of the exhalation valve. Further functions and advantages of the exhalation valve disclosed herein will be apparent from the detailed disclosure which follows.
In a preferred embodiment of the presently disclosed exhalation valve, a first sealing disc is spring-biased into sealing engagement with a valve seat. The first sealing disc is adapted to move out of engagement with the valve seat in response to a positive pressure within the inhalation system that exceeds a predetermined value. The predetermined value is established by the spring force applied to the first sealing disc. In a preferred embodiment, a plurality of constant force springs act on the first sealing disc to generate a relatively uniform resistance force.
In addition, a second sealing disc is preferably provided according to a preferred embodiment of the present disclosure. The second sealing disc is generally substantially coplanar with the first sealing disc, but of a lesser diameter (if the two discs are circular) or outermost dimension, as the case may be. The second sealing disc is generally resilient or flexible such that deflection of the disc along its surface is permitted. The second sealing disc is positioned in an adjacent, juxtaposed orientation relative to the first sealing disc, on the side of the first sealing disc opposite that against which the spring bias is applied.
Both first and second sealing discs generally include a first opening or aperture through which a mounting rod or nipple may pass. The first sealing disc also preferably includes at least one additional opening or aperture through which gas may be vented, as described herein. The second sealing disc is sized and dimensioned to overlie the at least one additional opening in an initial rest position, such that venting of gas therethrough is prevented. However, in response to an appropriate pressure force, the second sealing disc is adapted to flex or deflect such that the at least one additional opening is exposed and gas is free to pass therethrough. Once the appropriate pressure force is removed, the second sealing disc automatically returns to its initial non-flexed or non-deflected position, thereby preventing further flow of gases therethrough.